Added unit test for looping over: exp, frq, offset, point, time.
Regarding bug #21665, (https://gna.org/bugs/?21665) - Running a CPMG analysis with two fields at two delay times.
This unit test will fail, since the last loop over the time points has a weak assumption just to loop over all time points,
instead of checking for existence of such time point.
This unit test follows recommendation in thread: http://thread.gmane.org/gmane.science.nmr.relax.devel/5070.
